This invention relates to rotary hand tools, and it relates more particularly to lever-operated hand-powered tools for driving or removing screws, nuts or bolts and the like.
Numerous hand-powered tools have been devised heretofore, such as the spiral ratchet tools currently available. In this type of tool, it is necessary to apply the driving force for rotating the spindle in a direction lengthwise of its axis. Such an arrangement requires more space to operate than is available in many situations where the tool might be used, and is sometimes awkward to handle, especially where the tool is used for removing screws when the driving force along the length of the spindle tends to press the screw into place instead of removing it. Such tools also require two hands to operate, and the forces exerted are not efficiently applied.
A pistol-grip type of hand-powered tool, on the other hand, is more adaptable to the human hand because only the squeeze of the fingers is utilized to rotate the spindle, while the desired amount of pressure for forcing the screw or other fastener into place is applied with the palm of the hand on the grip of the tool independently of the force required to rotate the spindle. U.S. Pat. No. 3,035,451 to O'Connell et al discloses a pistol-grip type of hand-powered rotary tool in which the direction of rotation of the spindle is reversed by shifting the pinion on the spindle laterally into engagement with one or the other of a pair of beveled gears located on opposite sides of the pinion. A similar type of bevel-gear drive is disclosed in U.S. Pat. No. 3,132,549 to Lee, but in this case the two bevel gears are alternatively shifted into engagement with the pinion on the spindle for reversing its direction of rotation. The difficulty with both these bevelgear mechanisms is that in order to reverse the spindle, it is necessary either to shift the pinion gear and spindle laterally into engagement with one of a pair of bevel gears, or to shift the bevel gears into engagement with the pinion gear. In both cases, the spindle can be mounted only at one end of the housing for the tool. Furthermore, in the case where the spindle must be moved laterally, the mounting therefor is complicated and is characteristically unreliable.
It is an object of the present invention to provide a simple hand-grip tool with a bevel-gear drive and spindle-reversing mechanism, in which both the spindle and bevel-drive gear are sturdily mounted in the housing of the tool for smooth reliable operation.